"KS" stands for Kichizaemon Sumitomo, the head of the family-run conglomerate, who provided financial support for the research leading to KS Steel's invention.
[1] After World War one, when Japan had to cope with painful restrictions on imports of materials from foreign countries such as Germany, physicist Kotaro Honda was motivated to study alloys due to the need of a domestic steel production.
[2] The initials KS in the name of the steel come from Kichizaemon Sumitomo, who was the head of the family that provided financial support for the research leading to the invention.
KS steel is best tempered when heated to 950 °C and then quenched in heavy oil.
The maximum energy product (BH)max of KS steel is 30 kJ/m^3.